Chronic stable plaque psoriasis (Psoriasis Vulgaris) is the commonest form of the disease, accounting for 85-90% of cases. The circumscribed infiltrated skin lesions are scaly and erythematous and often symmetrically distributed over the body. Several types of palliative therapies exist. The therapies are either topical or systemic. The severity of chronic plaque psoriasis is often determined by the percentage of body surface area (BSA) involved. For mild, moderate and severe chronic plaque psoriasis with BSA involvement of up to 20%, initial therapy is topical. Phototherapy and numerous systemic therapies are usually indicated when more than 20% of skin is affected.